As aircraft systems become increasingly complex, there is an ever-increasing need to provide simple and efficient ways for operators to interface with these vehicles. In designing modern aircraft cockpits, aircraft designers and human factors engineers must consider the environment and flight envelope in which the aircraft will operate, pilot workload, and the maintainability of the aircraft. For example, most modern fighter aircraft are designed so that the pilot can operate many of the major systems on the aircraft (e.g., flight control surfaces, thrust control, radar, and fire control system) while maintaining the pilot's hands on the throttle and control stick (HOTAS). Additionally, more and more systems on modern aircraft are becoming computer mediated, changing the way in which the pilot interfaces with various systems. For example, many onboard and data link systems require the pilot to scroll through and select items off series of lists.
Although conventional optical encoders having scroll and select functions are well known and widely used to interface with personal office computer, the conventional optical encoders are not suitable for the harsh operating conditions that modern day aircraft experience. For example, the conventional optical encoders lack the required reliability; resistance to vibration, shock, and normal acceleration; resistance to sand, dust, and liquid; resistance to high intensity radiated fields, and resistance to electromagnetic interference with or from other systems. Furthermore, these devices lack the tactile feedback, small size, and structural framework for installation into an aircraft throttle or stick for mission segments where HOTAS operation is desirable.